Rubbing machine



Aug. 5, 1941.

G. H. EKSTROM RUBBING MACHINE Filed Nov. 6, 1937 und.:

Patented ug. 5, 1941 RUBBING MACHINE GustafA H. Ekstrom, Rockford, Ill., assignor to Sundstrand- Machine Tool Co., Rockford, Ill., a' corporation of Illinois Application November 6, 1937', Serial No. 173.264

Claims.

The invention relates generally to a rubbing machine and more particularly to a rubbing machine of the pneumatically actuated type.

A general obj-ect of the invention is to'provide a. rubbing machine of new and improved construction rendering the machine unusually light to facilitate handling thereof.

Another object of the invention is to perfect a pneumatically actuated rubbing machine of new and improved construction which is unusually light and yet is free from vibration.

A further object is to provide a rubbing :machine so constructed that the reactions of the pistons; and of the rubbing shoes or pads are balanced and opposed so that they are counteracted to eliminate Vibration and turning of the rubbing machine.

Yet another object is to perfect a pneumatically actuated rubbing machine having a pair of pistons disposed in aline and each actuating a rubbing shoe with the shoes disposed parallel with one another and side` by. side,r and withthe pistonsy and shoes moving in opposite directions so as to counterbalance the forces acting on the pistons and on the shoes.

Other objects and advantages will become apparent from the following -detailed description taken in connection withthe accompanyingdrawing, in which:

Fig. 1 is a vertical longitudinal sectional view of thel body of. a. rubbing machine embodying the features of the invention.

Fig. 2 is a top plan View of the machine shown in Fig.. l, partially inv section along the line22` of Fig. 1, better tovshow the valve and Valve` ports.

Fig. 3 is a `transverse. sectional View taken along the line.3--3` of. Fig. l.

Fig. 4 is a View taken along the line 4 4! of- Fig. 3, looking in the directionof the arrows.

While the invention is` susceptible of various modifications and alternative constructions, it is shown in the drawing and will be described hereinafter in a preferred embodiment, but it is not intended that the invention is to be limited thereby. to the specific construction disclosed, but it is intended-to cover all modications and alternative constructions falling Within the spirit and scope of the invention as defined by the appended claims.

Asshown in the drawing for purposes of disclosure, the rubbing machine 'comprises generally a body I I), constituting a housing for motor means and val-ve meansand a pair of rubbing shoes II slidably supported beneath the body and adapted to be actuated by the motor means. The body I il is -composed of an elongated casting I2 ofv some light Weight material, preferably aluminum, and, as best seen in Fig. 3, has in transverse cross section acylindrical intermediate portion I3, a flat base portion I4, and a top portion I5- having bulging sides I6, preferably hollow, which serve as" a grip for handling the rubbing machine. The cylindrical intermediate portion I3 of the casting I2, which may be formed b-y boring from end to-end of the casting I2; has a sleeve Il fitted therein which sleeve also extends from end to end ofA the casting. This sleeve forms the cylinders of the motor means and in order thatv there maybe two motor means a circular plug I8 preferably of brass is pressed into the sleeve and positioned centrally thereof. To complete the cylinders, the external ends thereof are closed by means of a cap Ill` and a cap 2li-suitably secured as `by bolting to the ends of the casting I 2.

Reciprocable in each of the cylinders thus formed within the casting I2 isa piston` 23 having a piston ring 24 at each end so as to make the piston. double acting. Preferably each piston is also cutaway intermediate its ends as at 25 to reduce the amount of material inA the piston and hence the weight thereof. It is gto be noted from the foregoing that the'pistons are in line and, moreover, are on the horizontal center and substantially on the vertical center of the machine.

Each of the pistons 23 is adapted to actuate a rubbing shoe I I-Which shoes herein are disposed side by side and parallel with one another. AccordinglyA there is secured to the bottom or base I4 of the casting I2v axbearing; plate 2.1 having serrations 28 extending longitudinallyA thereof. This plate may beremovably secured to the base I4 as by screws 29 (see-V Fig. 4). Slidable on the bearingy plate 21 and having-complementary serrations are two L-shaped slides 3U (see Fig. 4) disposedV in reversedlposition so that thelongitudinal legs are disposed opposite one another. Each of the slides 30" is secured to one of the pistons 23 by means of a pin 3"I'iixed` diametri- -cally of. the pistoncentrally thereof and having one end projecting through an elongated slot` 32 formed for that.. purpose in the bottom of the sleeve II andthe base portion I4 of the. casting- I2 and a. slot 321 `formed in the` bearing plate 21. The projectingend of' the pin 3|*A is made fast to the slide 30- So'that` the slide-Will be retained on the bearing plate 21 and will be reciprocated with the piston 23 as the latter reciprocates in its cylinder. Side gibs 33 further aid in guiding and retaining the slides 35 on the bearing plate 21.

Secured to each slide 35 is one of the rubbing shoes II and to that end each slide is formed with a block 35 to which a shoe II may -be removably secured as by screws 35. The shoes in turn in conventional manner carry a pad 31, usually of rubber, and a felt pad 3S over which a strip of sandpaper 39 is mounted. Herein the sandpaper is secured simply by folding the same inwardly over the ends of the shoe lI and securing the ends of the strip Vbeneath a spring member 40 terminating in teeth 4|. The spring member 4D is riveted at its inner end to the shoe I I and in order to add to the strength thereof has superimposed on it a second leaf spring 42.

InA order to effect reciprocation of the pistons 23 by the application of pneumatic pressure, the body ofthe rubbing machine is provided with suitable passages for the supply and exhaust of air and with a valve mechanism generally designated controlling the supply and exhaust of the air to and from opposite ends of the cylinders in timed relation with the reciprocation of the pistons, in order to effect continuous operation ofthe machine. To that end the casting I2 is provided in its top portion I5 with a valve chamber Y45 and mounted in the chamber is a valve 41. Preferably, to insure a better seal, the valve 41 operates in an annular valve sleeve 48 which, as bestseen in Fig. 2, is provided with six radial ports PI, P2, P3, P4, P5 and P5. Of these, ports PI and P2 are exhaust ports and communicate respectively with exhaust passages 49 and 50 extending longitudinally centrally of the portion I5 and opening through the ends of the 'casting I2.- The passages 49 and 50 are continued as 49 and 59', respectively, in the end caps 25 and I3 and are directed downwardly so as to discharge onto the surface being rubbed or polished so as to aid in keepingthe surface clean. Ports P3 and P4 serve alternately as inlet and exhaust ports and communicate respectively (see Fig. 2)` with passages 5I and 52 extending parallel with the passages i419 and 50 on opposite sides thereof and leading Vby means of inclined passagesfl and 52 respectivelyto the outer ends of the cylinders in which the pistons 23 reciprocate. Like passages 49 and 50, passages 5I and 52 are readily formed by drilling through the ends of the casting I2 with the ends of the passages opening through the ends of the casting I2 blocked by the caps I9 and 25.v Ports P5 and P5 also servealternately as inlet and exhaust ports and communicaterrespectively through short horizontal ducts with vertical passages 53 and 54 leading to the inner ends of the cylinders. The

casting I2 is formed with yet another passage 55 extending parallel with the passage 5!) on the opposite side from the passage 52 and this passage '55 constitutes an air supply passage. To that end it opens through the end of the casting I2 and registers with' a passage 55 in the cap I9 which terminates in a large port 51 threaded for thereception of an air hose. At its inner end the passage 55 extends upwardly and opens into the valve chamber 45 above the valve 41 therein.

In` order suitably to distribute the air supplied through the passage 55, the valve 41 is formed withtwo vertical passages 55, opening through the top of the valve so as to communicate with the valve chamber 45 and the supply passage 55, which passages terminate at their lower ends in radial ports 5I disposed diametrically opposite one another. The valve 41 is also undercut externally on diametrically opposite sides and on sides between the ports 5I with slots 52 of suicient length to embrace two adjacent ports. From the foregoing description, it will be apparent that by oscillating the valve 41 the ports 5I may be made to register with the ports P5 and P5 for supplying air under pressure to the inner ends of the cylinders 23, while at the same time the slots 52 will bridge the ports PI and P3 and P2 and P4 to connect the opposite ends of the cylinders to exhaust, while oscillation of "the valve in the opposite direction will cause ports 6I to register with the ports P3 and P4 whereby air under pressure will be supplied to the outer ends of the pistons 23, while ports P5 and P6 will be connected respectively with exhaust ports P2 and PI. To facilitate insertion of the valve 41 in the valve bushing 48, the valve chamber 45 opens through the top of the casting I2 and is closed by a suitable plug 53.

To oscillate the valve 41 for causing the ports 5I to register alternately with the ports P3 and P4 and P5 and P5 in timed relation with the reciprocation of the pistons 23, the lower end of the valve is cleft to receive the rectangular end of a wiggler stem 65 rotatably journaled in a bore drilled vertically through the plug I8 as well as through `the sleeve I1 and the intermediate cylindrical portion I3 of the casting I2. The lower end of the pin 55 extends into a circular recess 55 formed in the base portion I4. Rotatable in this recess and fixed to the projecting end of the pin 65 is a disk 51 formed with radial and diametrically opposite slots 63 in which are slidable blocks 59 each secured by a pin 10 to one of the slides 30. To accommodate the pins 10 the bearing plate 21 is provided with slots 'I I. With the blocks 59 free to slide in the slots 58, longitudinal reciprocation of the slides 30 will be converted into oscillatory movement of the pin 55 and the valve 41 thereby elfecting the supply of f air under pressure alternately to opposite ends of the pistons 23 to effect continuous reciprocation thereof. 'Ihe sides of the cleft in the lower end of the valve are not parallel but are diverging from the center of the valve so as to form with the rectangular end of the wiggler stem a lost motion connection. This connection enables the pistons 23 to travel througha portion of their stroke while the valve remains stationary with the ports in a particular registry, and as the pistons approach the end of their stroke in that direction the valve is suddenly rotated to effect an opposite registry of theports whereby movement of the pistons in the opposite direction is initiated.

It will be apparent from the foregoing that I have provided rst of all a rubbing machine which is unusually light in that it has an aluminum body and a minimum number of cylinders and other operating parts. The rubbing machine is also quickly and economically constructed since a 'majority of theA air passages may be formed by drilling and, similarly, the bore in which the cylinder sleeve I1 is received may be drilled. Moreover, of greatest importance is the arrangement and location of the pistons and the rubbing shoes and their mode of operation whereby the rubbing machine, though extremely light, is unusually free from vibration and from a tendency to rotate on the work being surfaced. Contributing largely to that feature is the Vconstructionlwhereby the pistons 23 are alined, and thefmode of operation ofthe pistons, with the result that the forces and reactions on the pistons areopposed so as to counterb-alance one another. Similarly, the parallel arrangement of the shoes Il with the motion in opposite direc-l tions also contributes to the stability of the machine.

I claim as my invention:

1. A rubbing Ina-chine of the character described having, in combination, pneumatic motor means comprising a body composed of an elongated casting having a longitudinally extending bore formed therein, a -cap secured over each end of said casting to close the outer ends of the bore, one of said end caps having a port for the reception of an actuating medium supply conduit, a transverse partition intermediate the ends of said casting dividing the bore into two alined cylinders of equal length, a piston reciprocable in each of the cylinders, and means for supplying and directing actuating medium to said cylinders comprising a valve chamber formed in the upper portion of said casting, passages formed in the upper portion of said casting leading from said valve chamber to both ends of both cylinders and to the port for the reception of an actuating medium supply conduit, passages leading from said valve chamber to atmosphere formed partly in the upper portion of said casting and partly in said end caps, a cylindrical valve in said valve chamber oscillatable to various positions to cause the simultaneous discharge of actuating medium alternately to the inner and outer ends of both a bore extending longitudinally thereof and opening through ,both ends thereof, a sleeve fitted in said bore and a cap secured over each end of said casting to close the outer ends of the bore, one of said end caps having a port for the reception of an actuating medium supply conduit, a plug fitted in the sleeve intermediate its ends to form of the sleeve two alined and independent cylinders, a piston reciprocable in each of the cylinders, and means for supplying and directing the actuating medium to said cylinders comprising a valve chamber formed in said casting, a valve oscillatable in said chamber, a supply passage formed in said casting opening at one end to said valve chamber and communicating at the other end with the port in one of the end caps, passages leading from said valve chamber to the inner and the outer ends of said cylinders and. exhaust passages leading from said valve chamber to atmosphere, said valve being ported in one position to connect the supply passage with the passages leading to the inner ends of both cylinders while the outer ends of both cylinders Iare connected to the exhaust passages and in another position connect the supply passage with the passages leading to the outer ends of both cylinders while the inner ends are connected to the exhaust passages, to effect reciprocation of the pistons in opposite directions, and means for. oscillating the valve in timed relation with the reciprocation of said pistons. Y

3. In a rubbing machine of the character described, a pneumatic motor means comprising an elongated casting forming a housing having in transverse cross section a cylindrical intermediate portion and a hollow top portion with sides bulging laterally beyond the intermediate portion to constitute a grip for holding the machine, a cylindrical sleeve extending longitudinally of said intermediate cylindrical portion from end to end of the casting, a cap secured over each end of the casting for closing the ends of said sleeve, a circular plug disposed in said sleeve midway between the ends thereof to divide the sleeve into two longitudinally extending and vaxially alined cylinders of equal length, a piston reciprocable in each of said cylinders so formed, and means for controlling the supply of actuating medium to said cylinders comprisingva valve chamber formed in the upper portion of said casting, passages leading from said valve chamber to -both ends of both cylinders, to the atmosphere, and to a supply conduit for actuating medium, a cylindrical valve in said valve chamber oscillatable to various positions to cause the simultaneous discharge of actuating medium alternately to the inner and the outer ends of both cylinders to effect simultaneous reciprocation of the pistons either inwardly toward or outwardly from the plug, and means actuated in timed relation with the reciprocation of said piston including a Wiggler pin extending through said plug and at its upper end engaging said valve to oscillate the same.

4. A rubbing machine of the character described having, in combination, pneumatic motor means comprising a body -composed of an elongated casting having a longitudinally extending bore formed therein, a cap secured over each end of said casting to close the outer ends of the bore, a transverse partition intermediate the ends of said casting dividing the bore into two aligned cylinders of equal length, a piston reciprocable in each of the cylinders, and means for supplying and directing actuating medium to said cylinders comprising a valve chamber formed in the upper portion of said casting, passages formed in the upper portion of said casting leading from said valve chamber to both ends of both cylinders and to a supply port, passages leading from said Valve chamber to atmosphere, a valve in said valve chamber oscillatable to various positions to cause the simultaneous discharge of actuating medium alternately to the inner and outer ends of both cylinders to effect simultaneous reciprocation of the pistons either inwardly toward or outwardly away from said partition, and means actuated in timed relation with the reciprocation of said pistons having engagement with said valve to oscillate the same.

5. In a rubbing machine of the character described, a pneumatic motor means comprising an elongated casting forming a housing having in transverse cross section -a cylindrical intermediate portion and a hollow top portion with sides bulging laterally beyond the intermediate portion to constitute a grip for holding the machine, a cylindrical bore extending longitudinally of said intermediate cylindrical portion from end to end of the casting, a cap secured over each end of the casting for closing the ends of said bore, a wall disposed transversely of said bore midway between the ends thereof to divide the bore into two longitudinally extending and axially aligned cylinders of equal length, a piston reciprocable in each of said -cylinders so formed, and means for controlling the supply of actuating medium to said cylinders comprising a valve chamber formed in the upper portion of said casting, passages leading from said valve chamber to both ends of both cylinders, to the atmosphere, and to a supply conduit for actuating medium, a valve in said Valve chamber oscillatable to various positions to cause the simultaneous discharge of actuating medium alternately to the inner and the outer ends of Alooth cylinders to effect simultaneous reciprocation of the pistons either inwardly toward or outwardly from said wall, and means actuated in timed relation with the reciprocation of said pistons including a member extending through said wall and at its upper end engaging said valve to oscillate the same.

GUSTAF H. EKS'I'ROM. 

